Polyvinyl chloride-based resin molded product and method for manufacturing the same

ABSTRACT

The present invention provides a polyvinyl chloride-based resin molded product obtained by molding a resin mixture containing 3 to 15 parts by weight of calcium carbonate having an average primary particle size of 0.01 to 0.3 μm and 2 to 4 parts by weight of an impact modifier per 100 parts by weight of a polyvinyl chloride-based resin, wherein a Charpy impact strength at 23° C. is 20 kJ/m2 or more, and a weight reduction ratio is 1.5 mg/cm2 or less when the molded product is immersed in a 93% by weight sulfuric acid aqueous solution for 14 days in accordance with JIS K 6745, and a method for manufacturing the polyvinyl chloride-based resin molded product.

CROSS-REFERENCE TO RELATED APPLICATION

This non-provisional application claims priority under 35 U.S.C. §119(a) on Patent Application No. 2017-198973 filed in Japan on Oct. 13,2017, the entire contents of which are hereby incorporated by reference.

TECHNICAL FIELD

The present invention relates to a polyvinyl chloride-based resin moldedproduct containing an impact modifier and calcium carbonate and a methodfor manufacturing the polyvinyl chloride-based resin molded product.

BACKGROUND ART

Conventionally, a molded product using a polyvinyl chloride-based resinhas been molded by a method such as extrusion molding, press molding,injection molding, or calender molding, and has been widely used forvarious products such as a pipe, a joint, a drainage basin, a gutter, awindow frame, a siding, a film-sheet material, a flat plate, and acorrugated plate.

In the molded product, a methyl methacrylate-butadiene-styrene graftcopolymer (MBS polymer), an acrylic rubber, or the like is often used asan impact modifier. Examples thereof include Patent Document 1 listedbelow. However, compounding of the above impact modifier causes aproblem such as a decrease in softening temperature, and further causesan increase in cost.

Therefore, Patent Document 2 listed below is an example in which theaddition amount of the impact modifier is suppressed by containingcalcium carbonate. However, dispersibility of calcium carbonate in amolded product is insufficient, and therefore an impact strengthmodifying effect thereof is limited. Furthermore, addition of a largeamount of calcium carbonate is necessary, and therefore this leads todeterioration in physical properties of a molded product, such aschemical resistance.

CITATION LIST

Patent Document 1: JP-B S51-25062

Patent Document 2: JP-A 2014-231565

SUMMARY OF THE INVENTION

The present invention has been achieved in view of the abovecircumstances. An object of the present invention is to provide apolyvinyl chloride-based resin molded product minimizing the additionamount of an impact modifier causing a decrease in softening temperatureand an increase in cost and the addition amount of calcium carbonatecausing deterioration in physical properties such as chemicalresistance, and having excellent impact resistance, and a method formanufacturing the polyvinyl chloride-based resin molded product.

As a result of intensive studies to achieve the above object, thepresent inventor has found that a molded product of a resin mixturecontaining 3 to 15 parts by weight of calcium carbonate having anaverage primary particle size of 0.01 to 0.3 μm and 2 to 4 parts byweight of an impact modifier per 100 parts by weight of a polyvinylchloride-based resin, particularly preferably the above molded productobtained by a molding method for promoting uniform dispersion of calciumcarbonate has excellent chemical resistance in addition to impactresistance, and has completed the present invention.

Therefore, the present invention provides the following polyvinylchloride-based resin molded product and a method for manufacturing thepolyvinyl chloride-based resin molded product.

1. A polyvinyl chloride-based resin molded product obtained by molding aresin mixture containing 3 to 15 parts by weight of calcium carbonatehaving an average primary particle size of 0.01 to 0.3 tan and 2 to 4parts by weight of an impact modifier per 100 parts by weight of apolyvinyl chloride-based resin, wherein a Charpy impact strength at 23°C. is 20 kJ/m² or more, and a weight reduction ratio is 1.5 mg/cm² orless when the molded product is immersed in a 93% by weight sulfuricacid aqueous solution for 14 days in accordance with JIS K 6745.2. The polyvinyl chloride-based resin molded product of 1 above, whereinthe impact modifier is at least one polymer material selected from thegroup consisting of a methyl methacrylate-butadiene-styrene graftcopolymer (MBS polymer), an acrylic rubber, and a chlorinatedpolyethylene.3. The polyvinyl chloride-based resin molded product of 1 above, usedfor a product selected from the group consisting of a pipe, a fitting, adrainage basin, a gutter, a window frame, a siding, a film-sheetmaterial, a flat plate, and a corrugated plate.4. A method for manufacturing a polyvinyl chloride-based resin moldedproduct, wherein a resin mixture containing 3 to 15 parts by weight ofcalcium carbonate having an average primary particle size of 0.01 to 0.3μm and 2 to 4 parts by weight of an impact modifier per 100 parts byweight of a polyvinyl chloride-based resin is mixed at a rotation-speedof 500 to 3,000 rpm and molded by a molding method selected from thegroup consisting of extrusion molding, press molding, injection molding,and calender molding to obtain a resin molded product in which a Charpyimpact strength at 23° C. is 20 kJ/m² or more, and a weight reductionratio is 1.5 mg/cm² or less when the molded product is immersed in a 93%by weight sulfuric acid aqueous solution for 14 days.

Advantageous Effects of the Invention

A polyvinyl chloride-based resin molded product according to an aspectof the present invention can suppress a decrease in softeningtemperature and deterioration in chemical resistance, has excellentimpact resistance, and is used advantageously for various applications.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Hereinafter, the present invention is described in more detail.

A polyvinyl chloride-based resin molded product according to an aspectof the present invention contains a polyvinyl chloride-based resin, animpact modifier, and calcium carbonate having a predetermined averageprimary particle size in predetermined amounts.

The polyvinyl chloride-based resin used in the present invention is avinyl chloride homopolymer, a copolymer of a vinyl chloride monomer anda monomer copolymerizable with vinyl chloride (usually a copolymercontaining 50% by weight or more of vinyl chloride), or a chlorinatedvinyl chloride copolymer. Examples of the monomer copolymerizable withvinyl chloride include a vinyl ester such as vinyl acetate or vinylpropionate, acrylic acid, an acrylate such as ethyl acrylate, amethacrylate such as methyl methacrylate or ethyl methacrylate, anolefin monomer such as ethylene or propylene, acrylonitrile, styrene,and vinylidene chloride. The polyvinyl chloride-based resin has anaverage polymerization degree preferably of 500 to 1,500, morepreferably of 700 to 1,300. With the average polymerization degree ofless than 500, impact strength is low, and requirement cannot besatisfied. With the average polymerization degree of more than 1,500,melt viscosity is high, and molding is difficult. Note that the averagepolymerization degree of the polyvinyl chloride-based resin is a valuemeasured by a melt viscosity method defined in JIS K 7367-2.

Calcium carbonate used in the present invention has an average primaryparticle size of 0.01 to 0.3 μm, preferably of 0.05 to 0.2 μm.Generally, as calcium carbonate in this average primary particle sizeregion, colloidal calcium carbonate synthesized by a chemical methodusing limestone as a raw material is commercially available. If theaverage primary particle size of calcium carbonate is within the aboverange, impact resistance of the polyvinyl chloride-based resin moldedproduct can be improved. As the particle size of calcium carbonatedecreases, the specific surface area thereof increases significantly,and it is considered that stress is diffused, and a microcraze isgenerated at a filler interface to absorb strain energy in a case whereimpact is applied. Note that the average primary particle size ofcalcium carbonate is measured by a transmission electron microscopephotograph observation method.

In particular, as the calcium carbonate, calcium carbonate which hasbeen subjected to surface treatment in advance and hardly agglomeratesis preferably adopted. In this case, a surface-treated calcium carbonatehas an average primary particle size of 0.01 to 0.3 μm. In a case ofusing calcium carbonate which has not been subjected to surfacetreatment, agglomeration tends to occur. If calcium carbonateagglomerates, an impact strength improving effect may be insufficient.In addition, calcium carbonate particles are desirably dispersed in apolyvinyl chloride-based resin molded product uniformly. Therefore,calcium carbonate has been desirably subjected to fatty acid surfacetreatment.

The fatty acid used in the surface treatment is preferably a higherfatty acid having 10 to 20 carbon atoms. Specifically, a fatty acid suchas stearic acid, palmitic acid, lauric acid, or oleic acid is preferablyused, and two or more kinds thereof may be mixed and used. Incidentally,as the fatty acid, not only a fatty acid but also a fatty acid salt withan alkali metal such as sodium or calcium, an alkaline earth metal, orthe like, or a fatty acid ester may be used.

The compounding amount of calcium carbonate is 3 to 15 parts by weight,and preferably 5 to 12 parts by weight per 100 parts by weight of apolyvinyl chloride-based resin. If the compounding amount of calciumcarbonate is within the above range, an impact strength modifying effectdue to some interaction with an impact modifier is exerted most, andimpact resistance of a polyvinyl chloride-based resin molded product canbe improved. If the compounding amount of calcium carbonate is less than3 parts by weight, an impact strength improving effect is hardlyexerted. If the compounding to amount of calcium carbonate exceeds 15parts by weight, a softening temperature significantly decreases, andchemical resistance is significantly deteriorated.

The impact modifier used in the present invention is at least one resinmaterial selected from the group consisting of a methylmethacrylate-butadiene-styrene graft copolymer (MBS polymer), an acrylicrubber, and a chlorinated polyethylene. In a preferable form, the impactmodifier is in a form of particles. Particles having an average particlesize of 5 to 500 μm are preferably used.

The compounding amount of the impact modifier is 2 to 4 parts by weightper 100 parts by weight of a polyvinyl chloride-based resin. If thecompounding amount of the impact modifier is less than 2 parts byweight, an effect of improving impact resistance is not sufficient. Ifthe compounding amount of the impact modifier exceeds 4 parts by weight,various properties such as tensile strength and softening temperatureare deteriorated.

As the above methyl methacrylate-butadiene-styrene graft copolymer (MBSpolymer), those known in the technical field may be used. Among thecompounds, a compound containing 40 to 85% by weight of butadiene in theresin is preferable. If the content of butadiene is less than 40% byweight, a sufficient impact resistance improving effect cannot beobtained. The content of butadiene of more than 85% by weight maydeteriorate fluidity and tensile strength.

The particle size of the methyl methacrylate-butadiene-styrene graftcopolymer is not particularly limited, but particles having an averageparticle size within a range of 10 to 350 μm are preferable.

As the acrylic rubber, those known in the technical field can be used.Examples thereof include a butyl acrylate rubber, a butadiene-butylacrylate rubber, a 2-ethylhexyl acrylate-butyl acrylate rubber, a2-ethylhexyl methacrylate-butyl acrylate rubber, a stearylacrylate-butyl acrylate rubber, and a composite rubber of asilicone-based rubber or the like and an acrylate rubber. Examples ofthe silicone-based rubber in this case include a polydimethylsiloxanerubber. Examples thereof further include, in addition to a ternarycopolymer obtained by adding methyl acrylate, ethylene, and a componenthaving a carboxyl group, a core-shell rubber obtained by grafting methylmethacrylate, an acrylate, or the like to a rubbery core formed ofstyrene butadiene or an acrylate.

The chlorinated polyethylene preferably has a chlorine content of 25 to50% by weight. A chlorinated polyethylene having a chlorine content ofless than 25% by weight has poor rubber elasticity and poor impactresistance. A chlorinated polyethylene having a chlorine content of morethan 50% by weight is too soft and may cause deterioration in heatresistance and tensile strength.

The chlorinated polyethylene is preferably amorphous, and particularlypreferably has a Mooney viscosity ML (1+4) (121° C.) in a range of 70 to120 from a viewpoint of improving impact resistance.

To the polyvinyl chloride-based resin molded product used in the presentinvention, a heat stabilizer for a chlorine-containing resin may beadded in addition to these substances. This heat stabilizer is used forpreventing discoloration of a molded product or deterioration of themolded product due to cutting of a molecular chain by thermaldecomposition of a chlorine-containing resin and release of hydrogenchloride when a chlorine-containing resin composition is subjected tomolding processing. As the heat stabilizer, those conventionally usedfor a polyvinyl chloride-based resin molded product can be used, andexamples thereof include a metal compound such as calcium, barium, orzinc, a tin-based compound, and a lead-based compound. The compoundingamount of the heat stabilizer is not particularly limited. However, theheat stabilizer can be used preferably in an amount of 20 parts byweight or less, more preferably in an amount of 1 to 10 parts by weightper 100 parts by weight of a polyvinyl chloride resin. A lubricant, aprocessing aid, an ultraviolet absorber, an antioxidant, a pigment, orthe like may be added, if necessary. Each of these additives may beadded in a range of 20 parts by weight or less.

As described above, in the present invention, the polyvinyl chlorideresin, an impact modifier, and calcium carbonate are compounded inpredetermined amounts. As a method for obtaining the resin mixture, bymixing the resin mixture with a rotary mixer at a specific rotationalspeed to mold the resin mixture, a molded product minimizing theaddition amount of an impact modifier and the addition amount of calciumcarbonate and having both impact resistance and chemical resistance canbe obtained. Examples of the rotary mixer to be used include a Henschelmixer and a super mixer from a viewpoint of convecting and uniformlymixing the resin composition according to an aspect of the presentinvention.

The rotational speed of the rotary mixer is not particularly limited,but is preferably 500 to 3,000 rpm, and more preferably 1,000 to 2,500rpm. In a case where this rotational speed is less than 500 rpm,agglomeration of calcium carbonate occurs due to poor dispersion ofcalcium carbonate, and a molded product having high impact strengthcannot be obtained in some cases. Conversely, in a case where therotational speed exceeds 3,000 rpm, it may be difficult to uniformlycontrol a mixing temperature due to excessive heat generation. At thetime of stirring by the mixer, rotation mixing is performed at thetemperature of compounding materials of 10 to 40′C, preferably of 20 to30° C. When the temperature of the compounding materials reaches 100 to140° C., preferably 110 to 130° C. by raising the temperature, thecompounding materials are discharged to obtain a powder compound of theresin mixture. In this case, the mixing time of the compoundingmaterials may be set preferably to 0.05 to 1.0 hr, more preferably to0.05 to 0.5 hr.

A method for molding the powder compound (resin mixture) (also referredto as “main molding”) is not particularly limited, but is preferablyselected from the group consisting of extrusion molding, press molding,injection molding, and calender molding.

Before the molding, the powder compound may be subjected to preliminarymelt processing. Examples of this preliminary melt processing include amethod using a product obtained by extrusion molding or roll molding anda method using a product obtained by pelletizing the molded productpreferably to about 0.5 to 10 mm, more preferably to about 1 to 7 mm bychopping. Kneading is preferably performed at the preliminary meltprocessing set temperature of 140 to 200° C. for 2 to 12 minutes. In acase of preliminary melt processing using extrusion molding, forexample, a powder compound is melted at 140 to 180° C. using anextrusion molding machine, a screw speed is controlled to 10 to 60 rpmsuch that a pellet has a length of about 0.5 to 10 mm in a longitudinaldirection, and a pellet compound can be thereby obtained. In a case ofroll molding, a powder compound is put into a two-roll (for example, 3to 9 inches, about 10 to 30 rpm) and kneaded, for example, at 160 to200° C. for 1 to 30 minutes, preferably for 1 to 10 minutes to obtain athickness of 0.1 to 5 mm. By performing preliminary melt processingunder such conditions, it is considered that calcium carbonate can bemore uniformly dispersed at the time of subsequent main molding of theresin mixture.

After the preliminary melt processing, by molding the powder compound bythe various molding methods described above, a polyvinyl chloride-basedresin molded product as a main molded product can be obtained. As aspecific example of this molding processing, by pressing a pellet havinga desired weight or a roll sheet cut into a desired length underpreferable conditions of 150 to 250° C., pressure of 10 to 100 kg/cm²,and 1 to 30 minutes so as to obtain a desired shape, a pressed sheet(having a thickness preferably of 0.5 to 10 mm, more preferably of 3 to5 mm) is molded to obtain a molded sheet. In main molding processing,not only press molding but also extrusion molding may be selected. Inthis case, a pelletized preliminarily melted product is put into anextruder. Control is performed such that a resin temperature is 140 to200° C. and a rotational speed is 20 to 60 rpm, and an extrusion moldedproduct such as a square rod or a sheet can be obtained.

The polyvinyl chloride-based resin molded product molded in the presentinvention has a Charpy impact strength preferably of 20 kJ/m² or more,more preferably of 40 kJ/m² or more, still more preferably of 50 kJ/m²or more. The Charpy impact strength is measured in accordance with JIS K7111 under a condition of 23±2° C. If the Charpy impact strength is lessthan 20 kJ/m², cracking easily occurs at the time of use.

As chemical resistance of the polyvinyl chloride-based resin moldedproduct, a weight reduction ratio is preferably 1.5 mg/cm² or less, andmore preferably 1.0 mg/cm² or less when the molded product is immersedin a 93% by weight sulfuric acid aqueous solution at 55° C. for 14 daysin accordance with JIS K 6745. If the weight reduction ratio exceeds 1.5mg/cm², defects due to erosion are easily generated in use under anacidic atmosphere, leading to destruction of the molded product.

The molded product according to an aspect of the present invention canbe preferably used for various industrial products such as a pipe, ajoint, a drainage basin, a gutter, a window frame, a film-sheetmaterial, a flat plate, and a corrugated plate. Impact resistance andchemical resistance required for these industrial products varydepending on environments in which the industrial products are used.Therefore, impact resistance and chemical resistance required areappropriately selected in consideration of a use environment and aprocessing step.

EXAMPLES

Hereinafter, the present invention is described specifically withreference to Examples and Comparative Examples, but the presentinvention is not limited to the following Examples.

Examples 1 to 15 (1) Preparation of Polyvinyl Chloride-Based ResinCompound

Using a polyvinyl chloride resin “TK-1000 (average polymerizationdegree: 1,000)” manufactured by Shin-Etsu Chemical Co., Ltd., commonlyused in all the Examples, calcium carbonate having a predeterminedaverage primary particle size, an impact modifier, a heat stabilizer,and a lubricant were added such that the compounding materials andcompounding amounts (parts by weight) were as illustrated in Tables 1and 2. Using a 10 L Henschel mixer (FM10C/type 1) manufactured by NipponCoke & Engineering Co., Ltd. as a rotary mixer, the resulting mixturewas blended for 0.1 hours while being rotated and mixed at a rotationspeed of 1,800 rpm (provided that the rotation speed in Example 12 was2,400 rpm and the rotation speed in Example 13 was 1,200 rpm), and apolyvinyl chloride-based resin compound was discharged at 120° C. Notethat an ST blade (standard) was used as an upper blade, and an AO blade(standard) was used as a lower blade in the Henschel mixer.

(2) Preparation of Roll Sheet (Preliminary Melt Processing)

The polyvinyl chloride-based resin compound obtained above was kneadedwith a 6 inch two-roll for five minutes by performing control underconditions of a roll temperature of 170° C. and 20 rpm to form a rollsheet having a thickness of 0.7 mm.

(3) Preparation of Press Sheet (Main Molding Processing)

The roll sheet (thickness: 0.7 mm) was cut into a desired length,stacked so as to obtain desired parts by weight, and pressed underconditions of 180° C., pressure of 50 kg/cm², and five minutes to obtaina pressed sheet having a desired thickness.

Example 16

A polyvinyl chloride-based resin compound was prepared in a similarmanner to Example 1. However, preliminary melt processing and mainmolding processing were performed by the following methods to prepare anextrusion molded product.

<Preparation of Extruded Pellet (Preliminary Melt Processing)>

Using the prepared powder compound, an extruded pellet was prepared witha 50 mmϕ single-screw extruder. An extruded pellet was prepared using a50 mmϕ single-screw extruder of L/D=25 at a screw compression ratio CR:2.5 with a screen: #60×1 sheet at a screw rotation speed: 40 rpm atcylinder setting temperatures of C1: 140° C. C2: 150° C., C3: 155° C.,and C4: 160° C. (C1 was closest to a hopper, and then the powdercompound passed through C2, C3, and C4 in this order) at a die settingtemperature of 160° C.

<Preparation of Extrusion Molded Product (Main Molding Processing)>

Using the prepared extruded pellet, extrusion molding was performed witha 15 mmϕ different direction twin-screw extruder. Extrusion molding wasperformed using a 15 mmϕ different direction twin-screw extruder ofL/D=30 at a screw compression ratio CR: 2.5 with a die: 4×10 mm squarebar at a screw rotation speed: 40 rpm at cylinder setting temperaturesof C1: 140° C., C2: 150° C., C3: 160° C., and C4: 170C (C1 was closestto a hopper, and then the pellet passed through C2, C3, and C4 in thisorder) at a die setting temperature of 180° C.

Example 17

A polyvinyl chloride-based resin compound was prepared in a similarmanner to Example 1. However, preliminary melt processing was notperformed, and main molding processing was performed using a powdercompound in a similar manner to Example 16.

Comparative Example 1

The procedure was performed in a similar manner to that in Example 1except that the rotation speed of the 10 L Henschel mixer (FM10C/type 1)was 400 rpm.

Comparative Example 2

The procedure was performed in a similar manner to that in Example 1except that calcium carbonate was not compounded at all.

Comparative Examples 3 and 4

The procedure was performed in a similar manner to that in Example 1except that calcium carbonate was not compounded at all and that thetype of impact modifier was changed as illustrated in Table 3.

Comparative Example 5

The procedure was performed in a similar manner to that in Example 1except that the compounding amount of calcium carbonate was 20 parts byweight per 100 parts by weight of a polyvinyl chloride resin.

Comparative Example 6

The procedure was performed in a similar manner to that in Example 1except that no type of impact modifier was compounded at all.

The molded products in the above Examples and Comparative Examples wereevaluated for Charpy impact strength and chemical resistance by thefollowing methods.

<Charpy Impact Strength>

A Charpy impact test was performed at 23° C. in accordance with JIS K7111 to measure impact strength. A case where the Charpy impact strengthwas 20 kJ/m² or more was evaluated as “O”, and a case where the Charpyimpact strength was less than 20 kJ/m² was evaluated as “X”. Themeasured values and evaluation are illustrated in Tables 1 and 2(Examples) and Table 3 (Comparative Examples).

<Chemical Resistance>

A weight reduction ratio was determined when a molded product in eachexample was immersed in a 93% by weight sulfuric acid aqueous solutionat 55° C. for 14 days in accordance with JIS K 6745. A case where theweight reduction ratio of a molded product in each Example was 1.5mg/cm² or less was evaluated as “O”, and a case where the weightreduction ratio of a molded product in each example was more than 1.5mg/cm² was evaluated as “X”. The measured values and evaluation areillustrated in Tables 1 and 2 (Examples) and Table 3 (ComparativeExamples).

TABLE 1 Example 1 2 3 4 5 6 7 8 Resin Polyvinyl chloride resin 100 100100 100 100 100 100 100 compounding Calcium (I) Particle size 3 5 8 1012 15 5 10 (parts by carbonate 0.15 μm weight) (II) Particle size 0.10μm (III) Particle size 0.08 μm Impact Acrylic rubber 3 3 3 3 3 3modifier MBS polymer 3 3 Chlorinated polyethylene Heat Sn-basedstabilizer 2 2 2 2 2 2 2 2 stabilizer Ca soap 2 2 2 2 2 2 2 2 LubricantParaffin wax 1 1 1 1 1 1 1 1 Polyethylene wax 0.15 0.15 0.15 0.15 0.150.15 0.15 0.15 Manufacturing Mixer rotation 1,800 1,800 1,800 1,8001,800 1,800 1,800 1,800 conditions speed (rpm) Preliminary Roll RollRoll Roll Roll Roll Roll Roll melt processing Main molding Press PressPress Press Press Press Press Press processing Evaluation of Charpyimpact 20.6 62.2 85.1 95.1 82.4 76.5 22.4 89.5 physical strength (kJ/m²)◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ properties Chemical resistance: 0.38 0.52 0.71 0.86 1.121.32 0.49 0.91 weight reduction ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ ratio (mg/cm²)

TABLE 2 Example 9 10 11 12 13 14 15 16 17 Resin Polyvinyl chloride resin100 100 100 100 100 100 100 100 100 com- Calcium (I) Particle size 10 1010 10 10 10 pounding carbonate 0.15 μm (parts by (II) Particle size 1010 weight) 0.10 μm (III) Particle size 10 0.08 μm Impact Acrylic rubber3 3 3 3 2 4 3 3 modifier MBS polymer Chlorinated 3 polyethylene HeatSn-based 2 2 2 2 2 2 2 2 2 stabilizer stabilizer Ca soap 2 2 2 2 2 2 2 22 Lubricant Paraffin wax 1 1 1 1 1 1 1 1 1 Polyethylene wax 0.15 0.150.15 0.15 0.15 0.15 0.15 0.15 0.15 Manufacturing Mixer rotation 1,8001,800 1,800 2,400 1,200 1,800 1,800 1,800 1,800 conditions speed (rpm)Preliminary Roll Roll Roll Roll Roll Roll Roll Extrusion None meltprocessing Main molding Press Press Press Press Press Press PressExtrusion Extrusion processing Evaluation of Charpy impact 85.5 91.897.2 97.2 62.0 24.3 82.5 87.2 25.5 physical strength (kJ/m²) ◯ ◯ ◯ ◯ ◯ ◯◯ ◯ ◯ properties Chemical 0.77 0.82 0.83 0.88 0.86 0.87 0.84 0.84 0.87resistance: ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ weight reduction ratio (mg/cm²)

TABLE 3 Comparative Example 1 2 3 4 5 6 Resin Polyvinyl chloride resin100 100 100 100 100 100 compounding Calcium (I) Particle size 0.15 μm 1020 10 (parts by carbonate (II) Particle size 0.10 μm weight) (III)Particle size 0.08 μm Impact Acrylic rubber 3 3 3 modifier MBS polymer 3Chlorinated polyethylene 3 Heat stabilizer Sn-based stabilizer 2 2 2 2 22 Ca soap 2 2 2 2 2 2 Lubricant Paraffin wax 1 1 1 1 1 1 Polyethylenewax 0.15 0.15 0.15 0.15 0.15 0.15 Manufacturing Mixer rotation speed(rpm) 400 1,800 1,800 1,800 1,800 1,800 conditions Preliminary meltprocessing Roll Roll Roll Roll Roll Roll Main molding processing PressPress Press Press Press Press Evaluation of Charpy impact strength(kJ/m²) 18.2 17.4 15.8 11.5 81.9 16.7 physical properties X X X X ◯ XChemical resistance: 0.83 0.33 0.40 0.19 1.61 0.70 weight reductionratio (mg/cm²) ◯ ◯ ◯ ◯ X ◯

Details of resin compounding in the above Tables 1 to 3 are as follows.

-   Polyvinyl chloride resin: “TK-1000” (manufactured by Shin-Etsu    Chemical Co., Ltd., average polymerization degree: 1,000)-   Heat stabilizer: Sn-based stabilizer (octyltin mercapto or butyl tin    sulfide)-   Ca soap: calcium stearate-   Lubricant: paraffin wax or polyethylene wax (oxidation type)-   Calcium carbonate: Any one of the following three types of colloidal    calcium carbonate (I) to (III) is used.    -   (I) Fatty acid surface-treated product having an average primary        particle size of 0.15 μm    -   (II) Fatty acid surface-treated product having an average        primary particle size of 0.10 μm    -   (III) Fatty acid surface-treated product having an average        primary particle size of 0.08 μm    -   (The fatty acid used for the surface treatment of calcium        carbonate is a mixture of fatty acids typified by stearic acid,        palmitic acid, lauric acid, and oleic acid.)-   MBS polymer (methyl methacrylate-butadiene-styrene graft copolymer):    “B-562” (manufactured by Kaneka Corporation, D50=215 μm, butadiene    content: 70 wt %)-   Acrylic rubber: “FM-50” (manufactured by Kaneka Corporation. MMA    graft acrylic rubber. D50=173 μm)-   Chlorinated polyethylene: “ELASLEN 351A” [manufactured by Showa    Denko K.K., chlorine content: 35 wt %, Mooney viscosity 90 M (121°    C.)]

The results in Tables 1 and 2 indicate that in Examples 1 to 17, due tothe addition amount of each of the impact modifier and calcium carbonatewithin a predetermined range, a polyvinyl chloride-based resin moldedproduct in which the Charpy impact strength at 23° C. is 20 kJ/m² ormore and a weight reduction ratio is 1.5 mg/cm² or less when the moldedproduct is immersed in a 93% by weight sulfuric acid aqueous solutionfor 14 days can be obtained.

In addition, the results in Table 3 indicate that in ComparativeExamples 1 to 6, in a case where each of the impact modifier and calciumcarbonate is used singly, or in a case where the addition amount ofcalcium carbonate is large, physical property values that the Charpyimpact strength at 23° C. is 20 kJ/m² or more and a weight reductionratio is 1.5 mg/cm² or less when the molded product is immersed in a 93%by weight sulfuric acid aqueous solution for 14 days cannot be obtained.

Japanese Patent Application No. 2017-198973 is incorporated herein byreference.

Although some preferred embodiments have been described, manymodifications and variations may be made thereto in light of the aboveteachings. It is therefore to be understood that the invention may bepracticed otherwise than as specifically described without departingfrom the scope of the appended claims.

1. A polyvinyl chloride-based resin molded product obtained by molding aresin mixture containing 3 to 15 parts by weight of calcium carbonatehaving an average primary particle size of 0.01 to 0.3 μm and 2 to 4parts by weight of an impact modifier per 100 parts by weight of apolyvinyl chloride-based resin, wherein a Charpy impact strength at 23°C. is 20 kJ/m² or more, and a weight reduction ratio is 1.5 mg/cm² orless when the molded product is immersed in a 93% by weight sulfuricacid aqueous solution for 14 days in accordance with JIS K
 6745. 2. Thepolyvinyl chloride-based resin molded product of claim 1, wherein theimpact modifier is at least one resin material selected from the groupconsisting of a methyl methacrylate-butadiene-styrene graft copolymer(MBS polymer), an acrylic rubber, and a chlorinated polyethylene.
 3. Thepolyvinyl chloride-based resin molded product of claim 1, used for aproduct selected from the group consisting of a pipe, a joint, adrainage basin, a gutter, a window frame, a siding, a film-sheetmaterial, a flat plate, and a corrugated plate.
 4. A method formanufacturing a polyvinyl chloride-based resin molded product, wherein aresin mixture containing 3 to 15 parts by weight of calcium carbonatehaving an average primary particle size of 0.01 to 0.3 μm and 2 to 4parts by weight of an impact modifier per 100 parts by weight of apolyvinyl chloride-based resin is mixed at a rotational speed of 500 to3,000 rpm and molded by a molding method selected from the groupconsisting of extrusion molding, press molding, injection molding, andcalender molding to obtain a resin molded product in which a Charpyimpact strength at 23° C. is 20 kJ/m² or more, and a weight reductionratio is 1.5 mg/cm² or less when the molded product is immersed in a 93%by weight sulfuric acid aqueous solution for 14 days.